I. Snow Cover and Sea Ice

A 1. Nature of Antarctic snow cover

The recording of types of snow surface, as defined in Snow Structure and Ski Fields,† both at base and during journeys, is easily done and is of great importance in connection with appraising travelling conditions and the landing of aircraft. These records should, of course, be correlated with weather conditions. Examination of the walls of pits also yields information on the nature of the surface.

A 2. Changes of snow level. Precipitation

As stated by Dr. Brooks the problem of measuring snowfall has not been solved. Any attempt to collect snow above the level of drift is bound to be impracticable, since even in flat areas the upper limit of drift is often 30 to 40 ft. (9 to 12 m.) high. The measuring of accretion over a large flat surface is probably the best method at present, and was used at Hope Bay during 1946. Difficulty was experienced in finding an area that appeared to be free from eddies and therefore drifts; the one chosen was about a mile (1.6 km.) from the base and some 750 ft. (230 m.) above sea-level. This meant that observations were not carried out as frequently as was desirable. The average of measurements made from four stakes at the corners of a half-mile square would have given more reliable figures (cf. comment by A. Stephenson).

A 3. frequency of surface hoar, rime and depth hoar

Much rime was deposited on the northern end of Trinity Peninsula during April and May, 1946, at heights varying from 4000 ft. (1219 m.) to sea-level. Fog deposit was also observed at Hope Bay during this period. In Snow Structure and Ski Fields it is stated that no records of fog deposit had been received from polar regions.

A 4. Shapes and sizes of snowflakes and their connexion with meteorological conditions

An attempt to record the types of snowflake was made at Hope Bay in 1946, using a very simple descriptive nomenclature, e.g. simple hexagonal plates, complex six-rayed stars, spicular, granular, etc. No attempt to make detailed drawings was made except in the case of some rather unusual “bamboo-like” forms that were once observed. Advice as to a more scientific classification would have been of great use.‡

A 6. Snow swamps

Answering J. E. Fisher’s query, it has been found that the ice in the Crown Prince Gustav Channel, on the east coast of Graham Land, becomes swamped with slushy snow and water every summer. This is due to the accumulated winter and spring thaw water not being drained away through the ice beneath, except where tide cracks and other rifts occur. Two seasons’ observations have shown that these conditions extend over most of the Gustav Channel, covering an area of 500–1000 square miles (1300–2600 km.²) at sea-level and lasting about two or three weeks.

E 2. Local distribution of the pack ice

All the F.I.D.S. bases have been keeping records of the distribution and type of sea ice in their neighbourhood. The eventual correlation of such observations will give a much better idea of conditions around Graham Land. When plotting the distribution of the sea ice it was found useful to indicate the amount of ice cover in tenths, in the same way as meteorologists indicate cloud cover. It is difficult of course to identify the types and distribution of sea ice near the horizon and to distinguish between light and heavy pack.

E 4. Icebergs

Observations of the speed and direction of the drift of icebergs were carried out in 1945–46 in Antarctic Sound at the northern end of Graham Land. An apparent seasonal change in the direction of the current was observed.